Scroll fluid machine

ABSTRACT

A scroll fluid machine comprises a fixed scroll and an orbiting scroll that engages with the fixed scroll to form a compression chamber between the fixed and orbiting scrolls. Near the outer circumference of the fixed and/or orbiting scroll, an annular dust-seal groove is provided. In the groove, a dust seal fits to prevent a gas from coming into the compression chamber or from leaking out of the compression chamber. In the dust-seal groove, an annular holder or piece is provided to prevent heat from transferring to the dust seal.

BACKGROUND OF THE INVENTION

The present invention relates to a scroll fluid machine such as a scroll compressor or a scroll vacuum pump.

In the specification, the front and rear mean an entrance and bottom of a dust-seal groove.

JP6-207588A and JP3248618B2 disclose a scroll fluid machine such as a scroll compressor or a scroll vacuum pump, comprising a driving shaft having an eccentric axial portion; an orbiting scroll comprising an orbiting end plate having an orbiting wrap; a fixed scroll comprising a fixed end plate having a fixed wrap; and a self-rotation-preventing device for preventing the orbiting scroll from rotating on its own axis, the orbiting scroll being rotatably mounted around the eccentric axial portion, the fixed wrap engaging with the orbiting wrap to form a sealed chamber.

With the eccentric axial portion of the driving shaft and the self-rotation-preventing device, the orbiting scroll is eccentrically revolved so that the volume of the sealed chamber reduces towards the center for compression of a gas or increases away from the center for expansion.

The orbiting and fixed wraps comprise an involute-curve which increases in diameter gradually in a direction of rotation; a curve which comprises a plurality of short curves around the center or a combination of the two curves. A radial gap between the fixed and orbiting wraps is exactly defined not to contact the wraps to each other or not to open excessively.

Engagement grooves are formed at the ends of the fixed and orbiting wraps. A tip seal fits in the engagement groove to slide on the end plate of the facing end plate airtightly.

A dust-seal groove is formed in the outer circumference of the fixed or orbiting end plate and a dust seal fits in the dust-seal groove.

The dust seal prevents air from coming into a lower-pressure chamber in a vacuum pump or prevents a gas from leaking out of a higher-pressure chamber in a scroll compressor.

The dust-seal groove in which the dust seal fits is formed with the scroll when the fixed or orbiting scroll made of Al or light alloy is molded, or is cut mechanically after molding of the scroll.

Heat which is generated during operation around the driving shaft of the scroll or frictional heat of the tip seal with the end plate are transferred to the dust seal in the dust-seal groove of the scroll to cause the dust seal to deteriorate or to wear rapidly.

Air bubbles are inevitably generated in the fixed or orbiting scroll that is cast. If the air bubbles are produced in the side sealed by dust seal when the dust-seal groove is mechanically formed, sealing capability will become poor to make performance of the scroll fluid machine worse.

SUMMARY OF THE INVENTION

In view of the disadvantage in the prior art, it is an object of the invention to provide a scroll fluid machine that prevents transfer of heat generated around a driving shaft for a fixed scroll or an orbiting scroll or frictional heat of a tip seal with an end plate, to a dust seal thereby improving durability and achieving stable performance for a long time.

It is another object of the invention to provide a scroll fluid machine to prevent air bubbles exposing on the dust-seal groove.

BRIEF DESCRIPTION OF THE DRAWINGS

The features and advantages of the invention will become more apparent from the following description with respect embodiments as shown in accompanying drawings wherein:

FIG. 1 is a vertical sectional side view of a fixed scroll in a scroll fluid machine;

FIG. 2 is an enlarged vertical sectional side view of the first embodiment of a scroll fluid machine according to the present invention;

FIG. 3 is an enlarged vertical sectional side view of the second embodiment of a scroll fluid machine according to the present invention;

FIG. 4 is an enlarged vertical sectional side view of the third embodiment of a scroll fluid machine according to the present invention;

FIG. 5 is an enlarged vertical sectional side view of the fourth embodiment of a scroll fluid machine according to the present invention;

FIG. 6 is an enlarged vertical sectional side view of the fifth embodiment of a scroll fluid machine according to the present invention;

FIG. 7 is an enlarged vertical sectional side view of the sixth embodiment of a scroll fluid machine according to the present invention;

FIG. 8 is an enlarged vertical sectional side view of the seventh embodiment of a scroll fluid machine according to the present invention;

FIG. 9 is an enlarged vertical sectional side view of the eighth embodiment of a scroll fluid machine according to the present invention;

FIG. 10 is an enlarged vertical sectional side view of the ninth embodiment of a scroll fluid machine according to the present invention;

FIG. 11 is an enlarged vertical sectional side view of the tenth embodiment of a scroll fluid machine according to the present invention;

FIG. 12 is an enlarged vertical sectional side view of the eleventh embodiment of a scroll fluid machine according to the present invention;

FIG. 13 is an enlarged vertical sectional side view of the twelfth embodiment of a scroll fluid machine according to the present invention; and

FIG. 14 is an enlarged vertical sectional side view of the thirteenth embodiment of a scroll fluid machine according to the present invention

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT

FIG. 1 is a vertical sectional side view of a fixed scroll 1 of a scroll fluid machine.

The fixed scroll 20 has an involute-curve fixed wrap 23 on the front surface of a fixed end plate 22 having a cooling fin 21 on the rear surface. A driving shaft passes through an axial hole 24 at the center of the fixed end plate 22 via a bearing.

A tip seal groove 25 is formed at the front end of the fixed wrap 23 and a tip seal 26 fits in the tip seal groove 25.

A dust-seal groove 27 is formed in the fixed end plate 22 around the fixed wrap 23. A dust seal (not shown) fits in the dust-seal groove 27.

The present invention relates to a scroll fluid machine in which the dust-seal groove 27 is novel.

FIG. 2 shows an enlarged view of a dust-seal groove, which will be described.

Near the outer circumference of a fixed end plate 1 made of Al or its alloy, an annular holding groove 3 is formed around a fixed wrap 2. In the holding groove 3, an annular holder 5 is provided to have a dust-seal groove 4.

The annular holder 5 is made of steel having thermal conductivity lower than material of the fixed scroll and is cast together with the fixed end plate 1 when the fixed scroll is cast.

The holding groove 3 may be formed by cutting off the fixed end plate 1 of the cast fixed scroll, and the annular holder 3 is then fixed in the holding groove 3.

The annular holder 5 may be pressingly fitted into the holding groove mechanically, or may be fixed in the holding groove 3 by hot fitting or cold fitting.

In FIGS. 3-14, the same numerals are allotted to the same members as those in FIG. 2 and description thereof is omitted.

FIG. 3 shows the second embodiment in which the annular holder 5 has an unevenness 6 extending axially on the outer circumferential surface.

FIG. 4 shows the third embodiment in which the annular holder 5 has a circumferential unevenness 7 on the outer circumferential surface.

FIG. 5 shows the fourth embodiment in which the annular holder has a groove 8 radially in the outer circumferential surface. A plurality of grooves 8 have bottoms.

FIG. 6 shows the fifth embodiment in which the annular holder 5 has a through hole 9 radially of the fixed end plate 1.

FIG. 7 shows the sixth embodiment in which the annular holder 5 has side walls becoming gradually thicker towards the bottom of the holding groove 3.

FIG. 8 shows the seventh embodiment in which an annular projection 10 is radially formed from the outer circumferential surface of the annular holder 5.

FIG. 9 shows the eighth embodiment in which on an inner side surface of the dust-seal groove 4 of the fixed end plate 1 of the fixed scroll, an annular piece 11 made of metal having thermal conductivity lower than the fixed end plate 1 is fixed. The annular piece 11 may be pressingly fitted by a mechanical device or attached on the lower-pressure side surface of the dust-seal groove 4 by casting.

FIG. 10 shows the ninth embodiment in which metal that has thermal conductivity lower than the fixed end plate is attached on the lower-pressure side surface of the dust-seal groove 4 by plating or thermal spraying to form an annular pressure-receiving surface 12.

FIG. 11 shows the tenth embodiment in which an unevenness 13 is formed on the inner circumferential surface of an annular piece 11 made of metal having thermal conductivity lower than the end plate of the scroll.

FIG. 12 shows the eleventh embodiment in which the annular piece 11 comprises a gradually-thicker portion 14 towards the bottom of the dust-seal groove 4.

FIG. 13 shows the twelfth embodiment in which the annular piece 11 has an inward projection 15.

FIG. 14 shows the thirteenth embodiment in which the annular piece 11 has an outward projection 16 which forms a bottom wall of the dust-seal groove 4.

The foregoing merely relate to embodiments of the invention. Various changes and modifications may be made by a person skilled in the art without departing from the scope of claims wherein: 

1. A scroll fluid machine comprising: a fixed scroll having a fixed end plate; and an orbiting scroll having an orbiting end plate, a dust-seal groove being formed close to an outer circumference of the fixed and/or orbiting scroll, an annular holder that fits in the dust-seal groove, the annular holder being made of material having thermal conductivity lower than material of said scrolls and having a groove in which a dust seal fits.
 2. A scroll fluid machine of claim 1 wherein the annular holder is cast together with the scroll when the scroll is cast.
 3. A scroll fluid machine of claim 1 wherein the annular holder is fixed in the dust-seal groove.
 4. A scroll fluid machine of claim 1 wherein the annular holder is pressingly fitted in the dust-seal groove.
 5. A scroll fluid machine of claim 3 wherein the annular holder is fitted in the dust-seal groove owing to difference in thermal expansion rate.
 6. A scroll fluid machine of claim 1 wherein the fixed and orbiting scrolls are made of Al or Al alloy and the annular holder is made of steel.
 7. A scroll fluid machine of claim 1 wherein an unevenness is formed axially on an outer circumferential surface of the annular holder.
 8. A scroll fluid machine of claim 1 wherein an unevenness is formed circumferentially on an outer circumferential surface of the annular holder.
 9. A scroll fluid machine of claim 1 wherein a groove is radially formed on an outer circumferential surface of the annular holder.
 10. A scroll fluid machine of claim 1 wherein a hole goes through a bottom wall of the annular holder.
 11. A scroll fluid machine of claim 1 wherein a side wall of the annular holder becomes thicker towards a bottom.
 12. A scroll fluid machine of claim 1 wherein a radial projection is provided at a bottom of the annular holder.
 13. A scroll fluid machine comprising: a fixed scroll having a fixed end plate; and an orbiting scroll having an orbiting end plate, a dust-seal groove being formed close to an outer circumference of the fixed and/or orbiting scroll, an annular piece being formed on an inner circumferential surface of the dust-seal groove, the annular piece being made of metal having thermal conductivity lower than material of said scrolls.
 14. A scroll fluid machine of claim 13 wherein the annular piece is formed by plating.
 15. A scroll fluid machine of claim 13 wherein the annular piece is formed by thermal spraying.
 16. A scroll fluid machine of claim 13 wherein the annular piece has unevenness.
 17. A scroll fluid machine of claim 13 wherein the annular piece becomes thicker gradually towards a bottom of the dust-seal groove. 